Pre-stimulus endogenous activity modulates category tuning in - PowerPoint PPT Presentation

Pre-stimulus endogenous activity modulates category tuning in ventral temporal cortex Yuanning Li 1,2,3 , Michael Ward 3 , R. Mark Richardson 2,3 , Max G’Sell 4 , Avniel Singh Ghuman 2,3 1 Joint PhD program in Neural Computation and Machine Learning, Carnegie Mellon University 2 Center for the Neural Basis of Cognition, Carnegie Mellon University and University of Pittsburgh 3 Dept. of Neurological Surgery, University of Pittsburgh 4 Dept. of Statistics and Data Science, Carnegie Mellon University

Classic view of event-related responses ! = ' #() + + "#$% ! "#$% stim-onset time 1/13

Endogenous activity ! = ' #() + + #,-. + /′ "#$% ! "#$% stim-onset time 1/13

Endogenous activity ! = ' #() + ' %"# + +′ "#$% ! "#$% stim-onset time 1/13

Endogenous activity correlates to post-stim neural response % = ! $() + ! "#$ + +′ #$&" % #$&" ! "#$ % #$&" Arieli et al., 1996; Kisley and Gerstein, 1999; Basar, 1980; Brandt et al., 1991; Nikulin et al., 2007;Henriksson et al., 2015 stim-onset time 1/13

Endogenous activity correlates to behavioral perception ! = ' #() + ' %"# + +′ "#$% ! "#$% ' %"# behavior Thut et al., 2006; Busch et al., 2009; VanRullen et al., 2011; Ng et al., 2012; Henry et al., 2012, 2014; Kayser et al., 2016 stim-onset time 1/13

Endogenous activity correlates to behavioral perception ! = ' #() + ' %"# + +′ "#$% tuning ? ! "#$% ' %"# behavior Thut et al., 2006; Busch et al., 2009; VanRullen et al., 2011; Ng et al., 2012; Henry et al., 2012, 2014; Kayser et al., 2016 stim-onset time 1/13

What about category tuning? ! = ' #() + ' %"# + +′ "#$% ! "#$% stim-onset time 2/13

What about category tuning? ! = ' #() + ' %"# + +′ "#$% ! "#$% stim-onset time 2/13

What about category tuning? ! = ' #() + ' %"# + +′ "#$% ! "#$% stim-onset time 2/13

Does endogenous activity influence category tuning? ! "#$%&'() * +,- , * /0+ = 2(# 4 * +,- , 5 4 * /0+ ) 7 0+8/ stim-onset time 2/13

Does endogenous activity influence category tuning? ! "#$%&'() * +,- , * /0+ = 2(# 4 * +,- , 5 4 * /0+ ) 7 0+8/ stim-onset time 2/13

Does endogenous activity influence category tuning? ! "#$%&'() * +,- , * /0+ = 2(# 4 * +,- , 5 4 * /0+ ) 7 0+8/ stim-onset time 2/13

Does endogenous activity influence category tuning? ? ! "#$%&'() * +,- , * /0+ = 2(# 4 * +,- , 5 4 * /0+ ) 7 0+8/ stim-onset time 2/13

Does endogenous activity influence category tuning? ! "#$%&'() * +,- , * /0+ = 2(# 4 * +,- , 5 4 * /0+ ) ? 7 0+8/ behavior stim-onset time 2/13

Hypotheses • Pre-stimulus activity modulates the degree of category tuning in response to visual stimuli. 3/13

Hypotheses • Pre-stimulus activity modulates the degree of category tuning in response to visual stimuli. • The same aspect in pre-stimulus activity that modulates tuning also correlates with behavioral perception. 3/13

Experiments • Intracranial Electroencephalography (iEEG) • Total number subjects: 32 (Photo Credit: Adeen Flinker) 4/13

Experiments • Task: • 6 categories (faces, bodies, words, houses, tools, scrambled non-objects) • 1-back task to detect repetitions + + + + + 5/13

Experiments • Category-selective channels: 230 • faces, bodies, words, houses, tools, scrambled non- objects R L 6/13

Methods ! "#$%&'() * +,- , * /0+ = 2(# 4 * +,- , 5 4 * /0+ ) 7/13

Methods • Fit the discriminant model for category classification using only post-stimulus activity ! "#$%&'() * +,- , * /0+ = 2(# 4 * +,- , 5 4 * /0+ ) 7/13

Methods • Fix the post-stimulus discriminant component and optimize the previous model conditioning on pre- stimulus activity ! "#$%&'() * +,- , * /0+ = 2(# 4 * +,- , 5 4 * /0+ ) 7/13

Methods • Fix the post-stimulus discriminant component and optimize the previous model conditioning on pre- stimulus activity ! "#$%&'() * +,- , * /0+ = 2(# 4 * +,- , 5 4 * /0+ ) • Define: # 4 * +,- - (post-stimulus) category tuning • 7/13

Methods • Fix the post-stimulus discriminant component and optimize the previous model conditioning on pre- stimulus activity ! "#$%&'() * +,- , * /0+ = 2(# 4 * +,- , 5 4 * /0+ ) • Define: # 4 * +,- - (post-stimulus) category tuning • 5 4 * /0+ - (pre-stimulus) modulation index (MI) • 7/13

Does the inclusion of pre-stimulus activity improve categorical classification accuracy? 1.5 sensitivity index (d') 1 0.5 0 bodies faces words tools places scrambled 8/13

Does the inclusion of pre-stimulus activity improve categorical classification accuracy? *** evoked only 1.5 evoked + endogenous * *** *** sensitivity index (d') *** 1 ** 0.5 * p < 0.05 ** p < 0.01 *** p < 0.001 Paired t-test 0 bodies faces words tools places scrambled 8/13

Does the inclusion of pre-stimulus activity improve categorical classification accuracy? • YES. Conditioning on pre-stimulus activity functionally improves category tuning. *** evoked only 1.5 evoked + endogenous * *** *** sensitivity index (d') *** 1 ** 0.5 * p < 0.05 ** p < 0.01 *** p < 0.001 Paired t-test 0 bodies faces words tools places scrambled 8/13

Does the sa same e asp spec ects ts of pre-st stimulus activity also correlate with behavior performance? * 700 Reaction time (ms) 650 600 9/13 High pre-stim MI Low pre-stim MI Low pre-stim MI High pre-stim MI

Does the sa same e asp spec ects ts of pre-st stimulus activity also correlate with behavior performance? * 700 Reaction time (ms) 650 * p < 0.05 600 Permutation test 9/13 High pre-stim MI Low pre-stim MI Low pre-stim MI High pre-stim MI

Does the sa same e asp spec ects ts of pre-st stimulus activity also correlate with behavior performance? • YES. The same aspects in pre-stimulus activity that influences post-stimulus category tuning also correlates with perceptual behavior performance. * 700 Reaction time (ms) 650 * p < 0.05 600 Permutation test 9/13 High pre-stim MI Low pre-stim MI Low pre-stim MI High pre-stim MI

Main hypothesis • Pre-stimulus activity modulates the degree of category tuning in response to visual stimuli. • The same aspect in pre-stimulus activity that modulates tuning also correlates with behavioral perception. 10/13

Next questions • A reflection of fluctuations in global cognitive state (e.g. arousal/attention)? 10/13

Next questions • A reflection of fluctuations in global cognitive state (e.g. arousal/attention)? Significant cross-channel correlation? 10/13

Next questions • A reflection of fluctuations in global cognitive state (e.g. arousal/attention)? 20 15 Significant cross-channel correlation? counts 10 5 0 0 0.05 0.1 0.15 r 2 10/13

Next questions • A reflection of fluctuations in global cognitive state (e.g. arousal/attention)? 20 15 Significant cross-channel correlation? counts 10 It is a local process. 5 0 0 0.05 0.1 0.15 r 2 10/13

Next questions • A reflection of fluctuations in global cognitive state (e.g. arousal/attention)? • A reflection of infra-slow fluctuations seen in resting state? 10/13

Next questions • A reflection of fluctuations in global cognitive state (e.g. arousal/attention)? • A reflection of infra-slow fluctuations seen in resting state? Significant auto-correlation across consecutive trials? 10/13

Next questions • A reflection of fluctuations in global cognitive state (e.g. arousal/attention)? • A reflection of infra-slow fluctuations seen in resting state? Significant auto-correlation 1 across consecutive trials? 0.8 auto-correlation 0.6 0.4 0.2 0 -0.2 0 2 4 6 8 10 10/13 lags

Next questions • A reflection of fluctuations in global cognitive state (e.g. arousal/attention)? • A reflection of infra-slow fluctuations seen in resting state? Significant auto-correlation 1 across consecutive trials? 0.8 auto-correlation 0.6 ~15% of the total channels 0.4 ( p < 0.05 uncorrected) 0.2 0 -0.2 0 2 4 6 8 10 10/13 lags

Next questions • A reflection of fluctuations in global cognitive state (e.g. arousal/attention)? • A reflection of infra-slow fluctuations seen in resting state? 11/13

Next questions • A reflection of fluctuations in global cognitive state (e.g. arousal/attention)? No, the effects are spatially uncorrelated. • A reflection of infra-slow fluctuations seen in resting state? Only a very small portion of the channels show trial-by-trial auto-correlation in endogenous modulation of tuning. The majority are transient. 11/13

Conclusion • Pre-stimulus activity influences the degree of category tuning in response to visual stimuli. 12/13

Conclusion • Pre-stimulus activity influences the degree of category tuning in response to visual stimuli. • The same aspects in pre-stimulus activity that influences post-stimulus category tuning also correlates with perceptual behavior performance. 12/13